Ask An Expert: Mechanical Heart Valves

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Ask An Expert: Mechanical Heart Valves

Question:

What makes a mechanical heart valve go bad? Is it possible to have one that is too small?

Answer:

These are two separate issues, and they are both important. First, mechanical valves hardly ever break down, but there have been a few models in which problems have occurred, such as cracks in the metal "struts" that make up the valve. When such fractures occur, the results can be disastrous. Fortunately, these events are quite rare. Another reason for a faulty heart is the development of bacterial infection in the tissues around the valve, a condition called "endocarditis." This can be a life-threatening problem that requires treatment with intravenous antibiotics. Treatment is especially challenging in someone with an artificial heart valve, even if the valve is still functioning.

During some types of dental work and medical procedures, bacteria can enter the blood stream. To help prevent bacteria from sticking to an artificial valve, doctors will recommend treatment with antibiotics before the dental or medical procedure.

Now, the second question you raise is one that is often overlooked. If the surgeon puts too small a valve in place, it may slow down blood flow even though the valve itself is working perfectly. When this happens, the patient may continue to feel short of breath and have evidence of heart failure, even though the valve itself is working just fine. Some patients even need to go back to the operating room to have a larger valve sewn into place.

Thomas Lee, M.D., is the chief executive officer for Partners Community HealthCare Inc. He is a professor of medicine at Harvard Medical School. He is an internist and cardiologist at Brigham and Women's Hospital. Dr. Lee is the chairman of the Cardiovascular Measurement Assessment Panel of the National Committee for Quality Assurance.

Last updated:	May 16, 2007